1. Field of the Invention
The present invention relates to a method for separating contaminants from olefin polymers. More particularly, the present invention relates to a method for removing residual catalyst components from an olefin polymerization product obtained in the presence of the catalyst.
2. Description of Related Art
The insufficient removal of catalysts and, in particular, their metallic and halogen components from liquid olefin polymer results in many undesirable problems. For example, the presence of catalyst residues may cause discoloration of the resulting polymerization products, the generation of hydrogen halide gas owing to the thermal degradation of the catalyst, the degradation or decomposition of the organic compounds owing to structural change during subsequent distillation, the poisoning by halogen contaminants of hydrogenation catalysts during subsequent polymer treatment, and the like. It is therefore desirable to remove the catalyst residues from the polymerization product as fully as possible prior to subsequent treatment and/or use of such products.
U.S. Pat. No. 3,904,498 discloses a process for removing residues of a catalyst comprising an aluminum compound of the formula AlRnX3−n wherein R is alkyl, X is halogen, and n is a whole or fractional number from 0 to 3 inclusive, from an organic solution containing the residues that comprises the steps of admixing an aqueous solution of an alkali or alkaline earth metal hydroxide with the organic solution to precipitate the catalyst residues as hydroxides or salts and separating precipitated catalyst residues from the resultant mixture, which is characterized by:    a. admixing the aqueous solution in an amount insufficient to form a second liquid phase in the resultant mixture, and forming a non-aqueous suspension of directly separable precipitated catalyst residues; and    b. separating the precipitated catalyst residues in the solid phase directly from the resultant mixture.
U.S. Pat. No. 4,028,485 discloses a process for removing hydrogenation catalyst residue from solutions of hydrogenated olefins or olefinic polymers containing them comprising treating such solutions with a non-aqueous acid followed by neutralization with an anhydrous base and filtration.
U.S. Pat. No. 4,122,126 discloses a method for removing an aluminum halide or its complex catalyst from a polymerization product comprising the steps of adding to the polymerization product an aprotic polar solvent in an amount of 1.0 through 6.0 mol per one mol of the aluminum halide in the catalyst present in the product and sufficiently mixing them at a temperature of 70° through 150° C., and then, filtering the mixture at a temperature of 70° through 150° C. The addition of the aprotic polar solvent facilitates the separation of the catalyst from the polymerization product.
U.S. Pat. No. 4,200,528 discloses that amorphous, hydrated magnesium silicate is effective in reducing the concentration of various metal ions in aqueous solutions or effluent streams. Both mono- and multi-valent ions can be treated in this manner, thereby providing a method of preventing release of metal ions to the environment. The method is said to be especially efficient in removal of chrome values from effluents generated in chrome tanning operations. Efficient adsorption of the chrome requires that the pH of the effluent-magnesium silicate slurry be adjusted to or maintained at a value between 5.3 and 9.8. The chrome value may be recovered from the magnesium silicate by acidification of the complex.
U.S. Pat. No. 4,207,152 discloses the removal of cationic contaminants from an alkali metal chloride brine by a process that comprises contacting the brine with solid particles of a magnesium-containing silicate having a mole ratio of silicon to magnesium of at least about 1:1. The cationic contaminants in the brine adhere to the magnesium-containing silicate particles and the concentration of the cationic contaminants is thereby reduced. A purified brine is obtained by removing the magnesium-containing silicate having cationic contaminants adhering thereto. Elements of Groups VIII, IV, and II can be removed from brines used in electrolytic processes, such as the production of chlorine and alkali metal hydroxides or alkali metal chlorates.
U.S. Pat. No. 4,256,577 discloses that the almost complete elimination of metal ions in aqueous effluents can be effected by treating the effluent with a base and then adding amorphous, hydrated magnesium silicate. This sequential process is said to allow metal ion concentration to be reduced to less than 0.1 part per million while using a fairly small amount of amorphous hydrated magnesium silicate.
U.S. Pat. Nos. 4,284,762 and 4,347,353 disclose an improvement in a method for inhibiting the corrosion-causing tendency and coloration of an olefin polymer or copolymer containing a halogen component by incorporating about 0.01 to about 5 parts by weight of a hydrotalcite; wherein the improvement comprises mixing an olefin polymer or copolymer containing a halogen component attributed to a polymerization catalyst and/or to post-halogenation, with a hydrotalcite of the formulaMg1−xAlx(OH)2An−x/n.mH2Owherein 0<x≦0.5, m is a positive number, and An− represents an anion having a valence of n, or a product resulting from the surface-coating of the hydrotalcite with an anionic surface-active agent, the hydrotalcite having (i) a BET specific surface area of not more than 30 m2/g, (ii) an average secondary particle size of not more than 5 microns, and preferably (iii) a crystallite size, in the <003> direction determined by an X-ray diffraction method, of at least 600 Å.
U.S. Pat. No. 4,379,882 discloses a polyolefin composition consisting essentially of (a) 100 parts by weight of a polyolefin containing halogens derived from a polymerization catalyst and/or attributed to the after-halogenation of the polymer, and (b) about 0.001 to about 10 parts by weight of an aluminum-magnesium hydroxide represented by the following formulaMg1−xAlx(OH)2+x.mH2Owherein x is a positive number represented by 0<x≦0.5 and m is a positive number represented by 0<m≦2, and having a BET specific surface area of no more than about 40 m2/g. A method for inactivating the halogen in a halogen-containing polyolefin is also disclosed.
U.S. Pat. No. 4,476,297 discloses that the content of titanium and light metal halides and aluminum compounds in polyolefins emanating from the catalyst system can be considerably reduced by treatment with a higher, preferably branched, aliphatic monocarboxylic acid having 6 to 10 carbon atoms.
U.S. Pat. No. 4,547,620 discloses a process for removing a halogen component from a halogen-containing organic compound, which comprises contacting an organic compound in the liquid state which is produced by using a halogen containing catalyst selected from the group consisting of Friedel-Crafts catalysts and Ziegler catalysts and contains the halogen component derived from the catalyst, with a hydrotalcite compound represented by the formulaM1−x2+Mx3+(OH)2+x−nyAyn−.mH2Owherein M2+ represents a divalent metal ion selected from the group consisting of Mg2+, Zn2+, Ca2+, Ni2+, Co2+, Mn2+ and Cu2+, M3+ represents a trivalent metal ion selected from the group consisting of Al3+, Fe3+ and Cr3+, An− represents an anion having a valence of n selected from the group consisting of HCO3−, OH− and CO32−, and x, y and m are each a positive number and satisfy the following conditions 0.1<x<0.5, 0.1<y<0.4, 0≦m<1, under non-aqueous conditions, and separating the treated organic compound from the hydrotalcite compound.
U.S. Pat. No. 4,642,408 discloses the removal of nickel, aluminum and chlorine derivatives, which remain dissolved in olefin oligomers after oligomerization in the presence of a catalyst comprising such derivatives, by treatment with: oxygen or a gas containing oxygen, anhydrous ammonia, and a solution of an alkali metal hydroxide.
U.S. Pat. No. 4,721,818 discloses a method for removing double metal cyanide complex catalyst residue from polyols using alkali metal hydrides. In one embodiment, the catalyst residue is converted into an insoluble ionic metal species and separated by filtration using magnesium or aluminum silicate to facilitate separation.
U.S. Pat. No. 4,877,906 discloses a method for removing double metal cyanide complex catalyst from polyether polyols which uses alkali metal compounds and phosphorous compounds to precipitate the residual catalyst, which may then be removed by filtration. In one embodiment, a propylene oxide polyol is treated with sodium metal dispsersion, capped with ethylene oxide, treated with magnesium silicate, and then filtered to remove at least a portion of the catalyst. Substantially complete catalyst removal is then achieved by treating the polyol with hypophosphorous or phosphorous acid to precipitate the remaining solubilized double metal cyanide complex catalyst residue, neutralizing the excess acid with magnesium silicate, and filtering.
4,992,529 discloses a method for separating metal residues from a polymer wherein a solution or suspension of the polymer is contacted with an aqueous solution containing one or more inorganic acids in the presence of a monocarboxylic acid containing from about 6 to about 20 carbon atoms. The polymer solution or suspension will be contacted with an oxidizing agent either prior to or simultaneously with the contacting with the aqueous inorganic acid solution. The inorganic acid is, preferably, a mineral acid and the monocarboxylic acid is preferably a branched chain alkanoic acid having from about 6 to about 10 carbon atoms. When a monocarboxylic acid is used in combination with the inorganic acid, the amount of metal removed from the polymer is said to be increased and the amount of the aqueous phase containing ionized metal entrained in the organic phase reduced.
U.S. Pat. No. 5,093,509 discloses the separation of an epoxidation reaction product formed by the molybdenum catalyzed reaction of propylene with tertiary butyl hydroperoxide to provide propylene oxide and tertiary butyl alcohol by distillation into a propylene fraction, a propylene oxide fraction, a tertiary butyl alcohol fraction and a heavy liquid distillation fraction composed primarily of tertiary butyl hydroperoxide, tertiary butyl alcohol, dissolved molybdenum catalyst, and impurities including lower aliphatic C1-C4 carboxylic acids, and the dissolved molybdenum content of the heavy distillation fraction is adjusted to about 300 to 500 ppm of dissolved molybdenum, if necessary, by treatment with a precipitating agent and contacted with a solid adsorbent consisting essentially of a synthetic, porous, high surface area amorphous magnesium silicate.
U.S. Pat. No. 5,104,972 discloses a process comprising the steps of contacting a Group VIII metal hydrogenation catalyst residue containing polymer solution with a silicate, and recovering a polymer solution comprising less than 5 ppm by weight, based on the solution, of the Group VIII metal. In a preferred embodiment, the silicate is calcium silicate, magnesium silicate or diatomaceous earth.
U.S. Pat. No. 5,196,630 discloses a simplified method for the removal of halogen containing catalytic residues from olefin polymerization products. A quaternary ammonium salt is employed as a treating agent to facilitate removal of greater than 95% of catalytic residues in a single caustic or water wash with less than 15 minutes of settling time required after the wash.
U.S. Pat. No. 6,180,730 discloses the use of a particulate deactivator to pacify halogen-containing catalyst residues from a medium pressure solution polymerization process. The deactivator is added post-reactor preferably in the form of a suspension. The particulate deactivator may also be used in conjunction with a secondary, soluble deactivator.
U.S. Pat. No. 6,274,777 discloses a method for removing boron from a boron trifluoride-catalyzed polyalkyl hydroxyaromatic reaction product which comprises: (a) diluting the polyalkyl hydroxyaromatic reaction product with an inert solvent to give a polyalkyl hydroxyaromatic reaction product concentration in the range of about 40 to about 80 weight percent; (b) filtering the diluted polyalkyl hydroxyaromatic reaction product in the presence of a filter aid in combination with (1) magnesium silicate, (2) water or (3) a mixture of magnesium silicate and water; wherein the water is present during filtration at a concentration of about 100 to 1,500 ppm, based on the diluted polyalkyl hydroxyaromatic reaction product; with the proviso that when water is used in the absence of magnesium silicate, the filter aid is diatomaceous earth; and (c) recovering a filtrate containing the diluted polyalkyl hydroxyaromatic reaction product having less than about 10 ppm of boron present.
The disclosures of the foregoing are incorporated herein by reference in their entirety.